Pallet tracking

Introduction

In this article we’ll cover some traditional and more novel technologies and solutions that can make it possible to track pallets throughout the entire supply chain, both outdoor and indoor, and that can make pallet handling more automated and error-proof.

Before we start, we have to make clear that, even though we are talking about pallet tracking, we are not so much interested in the pallet itself, but rather, we want to track the contents on the pallet, and we want to automate the forklift handling of pallets. In a typical operation, pallets can move from one site to another through a truck, and then, once inside the facility, it will be handled by a material handling equipment.

Typically, there is no visibility of where a pallet is, or how to handle it, until the pallet is scanned, and potentially it is also logged where the pallet is dropped, usually also by scanning a code of the location. In conclusion, lots of manual scanning, and lots of opportunity of errors resulting.

Indirect pallet tracking

Before looking at various tags and sensors to track pallets and their contents, we have to acknowledge that in practically all cases, it is simply way too expensive to equip a pallet or the boxes on it with a sensor that can either provide tracking on the road throughout various countries, for example with a GPS tracker, or too expensive to equip with a high-accurate indoor location tracker which can provide shelf-level of accuracy within the warehouse (for example with an UWB tracker). With over 5 billion pallets in use worldwide, it is simply impossible to equip those with trackers costing 30 to 60$ each. Only solutions that cost a few dollars, or even a few cents are viable when you have many pallets.

For this reason, it almost always doesn’t make sense to accurately locate the pallet itself, but rather to update the pallet’s location using the location of whatever vehicle or equipment is moving the pallet at that moment. For example, in Amazon warehouses, you can have mobile robots (AMR’s) that can accurately self-localize, trucks on the road can have GPS and forklifts can be accurately tracked with a real-time location system.  

In order for this to work, the vehicle that is moving the pallet must be able to detect and identify that it is carrying a certain pallet or container. Once you know that, you can easily update the pallet’s inventory location whenever it is picked up or dropped off by some tracked material handling equipment.

With this indirect pallet tracking it is possible to:

• eliminate the manual scanning of the drop-off location op pallets
• automate inventory bookings in the ERP system of the pallet’s storage location
• automate validation if pallets are dropped at the right location
• automate validation if pallets are put into the right trailer on the outbound dock
• automate validation that the right pallet is picked

Pallet tracking and identification technologies

Even with indirect pallet tracking, it is still critical that the pallet can be identified by the truck, forklift or AMR. Furthermore, in some cases we may even want to have some sensor information as well. In this section will look at various technologies that can be leveraged for this.

1. Barcodes

Barcodes are extensively used in any logistics operation. They are cheap and easy to use. In most operations, the barcode will get scanned manually by the operator whenever it is picked up or dropped off. Barcodes offer limited possibilities for automation. However, specifically for forklift it is possible to automate the scanning by having a barcode scanner mounted in the front of the truck. whenever something is loaded on the fork, all the barcodes can be read out in the blink of an eye to identify the pallet or its content.

2. RFID

RFID, and particularly UHF RFID is another commonly used technology for tracking pallets. RFID is also relatively cheap and easy to use. RFID can get detected whenever it is in range of an RFID scanner, which can scan all RFID labels, even when they are not visible. For RFID, more automation possibilities exist by installing RFID gates, for example at the dock doors, or by equipping forklifts with an RFID scanner in the front of the truck (similarly as with the barcode reader).

3. Bluetooth

With bluetooth trackers, it is possible to track pallets directly. Because these battery-powered trackers actively broadcast a signal, it is possible to easily pick up the presence of a pallet either inside a facility or inside a trailer of a truck. For this a BLE gateway is required which can scan these Bluetooth broadcasts. Given that the range of this is around 80m, it doesn’t require many gateways. Inside a truck, many of the bluetooth gateways are also equipped with GPS and cellular connectivity, which allows them to send the information on the scanned pallets to the cloud. With more ble gateways installed, it is even possible to track the location of the pallet with an accuracy of 5-10meters using bluetooth tracking.

Unfortunately, using this scanning to detect which load is on a forklift or on an AMR is less performant. While it is possible, it would typically take a longer time (tens of seconds) to reliably match the pallet with the forklift that picked it up. This is in part because of the high range of the bluetooth signal which can easily pick up other signals from neighboring pallets.

‍

Innovative Bluetooth and RFID smart labels

With the realization that all three technologies above have certain complementary advantages, a novel smart label was developed which combines all three technologies together. By leveraging the latest advancements in battery technology, which allow to have eco-friendly, low-cost, ultra-thin and bendable batteries, in combination with ultra-low power bluetooth technology it is possible to have a printable labels with bluetooth and RFID inside. By using off-the-shelf RFID label printers, any barcode or text can be printed on these labels.

‍

‍